Jan 10, 2015

A lizard's penis evolves six times faster than any of its other parts, a new study finds.

The study is the first to directly measure the evolution rate of the penis of any species, though researchers have long suspected that the male genitalia evolve faster than other body parts, said study researcher Julia Klaczko, a biologist at the University of Campinas in Brazil.

"What we see is, sometimes, very close species have very different hemipenes or genitalia," Klaczko told Live Science. Hemipenes are the pair of organs that make up the version of a penis found in snakes and lizards. But dramatic genital differences are seen among closely related animals with penises, as well.

Quick-changing penises

Because penises are often so different even in species that otherwise look almost identical, researchers frequently use genitals to discriminate between different species. Klaczko and her team chose to measure the genitals of 25 species of Anolis, a group of lizards that live in the Caribbean. Anolis lizards are a well-studied group, and researchers have lots of information about the relationships between the species, as well as their habitats and body shapes, Klaczko said.

The lizards' hemipenes are tubular structures with a groove through which semen can flow. The researchers measured the length and width of the hemipenes in several specimens of each species. For comparison, they also measured the length of the lizards' limbs, which evolve in response to the vegetation in the animals' habitats, and the size of their dewlaps, which are the flaps of tissue near the throat that the lizards use for communication.

Next, using mathematical modeling, the researchers estimated the rates of evolution necessary to arrive at the differences in genitals, limbs and dewlaps. The result? Male genitalia change six times faster than either legs or throat flaps, making them more diverse in shape and size from one another than the other body parts.Picky females or sexual warfare?

Klaczko and her colleagues aren't sure what drives the rapid alterations in hemipenes. One possibility is that females pick mates with pleasing penises, whether that means their genitals are more stimulating or a better "fit" in the female genitalia.

Another, less cooperative, possibility is that male and female lizards are locked in an evolutionary arm's race in which both are trying to control reproduction. If this is the case, then males may be evolving genitals that give them an advantage in fertilization, while females evolve their genitals in an attempt to take that advantage back.

One known example of such a sexual arms race is the duck. Some duck species have corkscrew vaginas that spiral in the opposite direction of the males' corkscrew penises, so the females can better resist unwanted mating attempts.

Analysis of fecal matter from the natural mummy of Cangrande della Scala, a medieval warlord and the patron of the poet Dante Alighieri, has established the Italian nobleman was poisoned with a deadly heart-stopping plant known as Digitalis or foxglove.

The most powerful man in the history of Verona, to whom Dante dedicated part of the “Divine Comedy,” Cangrande della Scala (1291-1329) died at the age of 38 on 22 July 1329.

“He became sick with vomit and diarrhoea just a few days after winning control over the city of Treviso,” Gino Fornaciari, professor of history of medicine and paleopathology at the University of Pisa, told Discovery News.

The Treviso victory was the last act in Cangrande’s long struggle to control the entire region of Veneto in northern Italy.

According to contemporary accounts, he had contracted the disease a few days before by “drinking from a polluted spring.”

Rumors of poisoning immediately started to spread. In 2004, 675 years after Cangrande’s death, Fornaciari’s team exhumed the nobleman’s body from a richly decorated marble tomb in the church of Santa Maria Antica in Verona.

“The natural mummy, still wearing its precious clothes, appeared in good state of preservation,” Fornaciari and colleagues wrote in the Journal of Archaeological Science.

Lying on the back with the arms folded across the chest, the 5-foot, 7-inch mummy was initially studied using digital X-ray and CT scans.

These showed regurgitated food in the throat, signs of arthritis in the elbows and hips, evidence of tuberculosis and possible cirrhosis.

The abdominal CT scans also showed the presence of feces in the rectum, allowing Fornaciari and colleagues to extract a sample.

Toxicological analyses confirmed concentrations of digoxin and digitoxin, two Digitalis glycosides, both in the liver and in the faeces.

“Although it is not possible to rule out totally an accidental intoxication, the most likely hypothesis is that of a deliberate administration of a lethal amount of Digitalis,” Fornaciari and colleagues concluded.

Indeed, the gastrointestinal symptoms showed by Cangrande in the last hours of his life and described by historical sources are compatible with the early phase of Digitalis intoxication.

According to the researchers, the foxglove poison may have been masked in a decoction containing chamomile, largely used as a sedative and antispasmodic drug, and black mulberry, used as astringent, which was prepared for some indisposition of Cangrande.

Jan 9, 2015

When bats take wing at night and hunt in groups, they improve their chances of finding the best bugs using a simple technique: They eavesdrop on each other, to the benefit of them all.

Just published in the journal Current Biology is a study out of Tel Aviv University that recounts this observed behavior in bats, which the authors called the "bag of chips effect."

"When you sit in a dark cinema theater and someone opens a bag of chips, everyone in the theater knows that someone is eating chips and approximately where that someone is," lead researcher Yossi Yovel explained in a statement. "Bats work similarly."

"Chips" for a bat, of course, would be a juicy patch of insects, and the scientists noted that when one bat hit paydirt, other bats close enough by to hear the score converged on the location.

The particular bat the researchers studied was the Rhinopoma microphyllum, otherwise known as the Greater Mouse-tailed bat. The food it chased was typically flying ant queens. That insect can be plentiful but well dispersed, in patches that are tough to find. So the bats' ability to snoop on each others' hunting improves their collective chance of dining well.

Such insect crowd-hunting skills are a beneficial trick for the bats, in light of the fact that while they can hear prey that comes within about 33 feet (10 meters) of them, they can hear one of their pals finding food from an astonishing 328 feet (100 meters) away.

Yovel and his colleagues rigged their study bats with very small, GPS-enabled ultrasonic recorders and then began collecting data.

The process, Yovel said, "allowed us to tap into the bats' sensory acquisition of the world by recording them." The sonar recordings allowed the researchers to be able to tell when the bats were hunting down prey and when they were simply conferring with other bats. "This is almost impossible to do with other animals," Yovel added.

The butterfly was determined to be a Lexias pardalis, and its condition is called bilateral gynandromorphy.

"Gynandromorphism is most frequently noticed in bird and butterfly species where the two sexes have very different coloration," Entomology Collection Manager and lepidopterist Jason Weintraub explained. "It can result from non-disjunction of sex chromosomes, an error that sometimes occurs during the division of chromosomes at a very early stage of development."

While scientists know the condition is very rare, it's not easy for them to gauge just how rare, because gynandromorphism can often be overlooked in species whose males and females look similar to each other.

The butterfly Johnson encountered came to the university in a shipment of pupa from a sustainable butterfly farm in Malaysia. Lexias butterflies, which don't have a standard colloquial name but are known as "brush-footed" butterflies, live in Southeast Asian rainforests.

The special half-and-half butterfly has been preserved and pinned and will be displayed at Drexel's Academy of Natural Sciences from Saturday, Jan. 17 through Monday, Feb. 16.

From genetics to life at home, there appear to be a number of factors that predispose some brothers to violent behavior.

So it may not be a coincidence that two sets of brothers have been identified as terrorist suspects -- Dzhokhar Tsarnaev and his slain brother, Tamerlan Tsarnaev, in the Boston Marathon bombing and, now, brothers Saïd Kouachi and Cherif Kouachi for the killing of 12 people at the offices of the Charlie Hebdo newspaper in Paris.

The Kouachi brothers were killed by police today as the pair held a hostage outside of Paris.

"There are numerous factors" that contribute to terror-related murders, "including neurobiological, personality, social and cultural," neuropsychologist Robert Hanlon of the Northwestern University Feinberg School of Medicine told Discovery News.

He added, "One brother is usually a stronger character and the leader of the two. The other brother is a follower and is influenced by the leader-brother. The follower wants to please the leader and obtain the respect of the leader."

Hanlon added that such siblings tend to be male, with men committing 90 percent of murders annually in the United States alone.

"Due to biological, psychological and socio-developmental differences between the genders, men are far more violent than women," he said.

In addition to terrorist duos, there are also a number of serial killers who are brothers, such as Pete and Pat Bondurant, Larry and Danny Ranes and Reginald and Jonathan Carr, just to name a few.

Terrorism is a subtype of violence that, as Hanlon indicates, can have multiple driving influences.

Neuroscientist Jeremy Richman of The Avielle Foundation added, "All of our behavior has both a genetic and environmental component -- they cannot be separated."

On the "nature" side of nature/nurture, two genes were recently discovered that increase a person's risk for violent behavior 13-fold: MAOA and CDH13. The research was led by Jari Tiihonen, a professor in the Department of Clinical Neuroscience at the Karolinska Institute in Sweden. He points out that men are more likely than women to carry the two genes.

"Since MAOA is located in the X-chromosome, men have only one copy of the gene and women have two copies," Tiihonen said, explaining that women have two X-chromosomes.

"Therefore, females can have one low-activity allele (alternative form of a gene that arises by mutation) and one high- activity allele, but if males have a low activity allele, they cannot have another allele functioning more efficiently because they have only one copy of the gene."

It's then possible that the genes are passed down in families, mostly affecting males. A forthcoming study on twins, which will be published in the journal Biological Psychology, found that some males, even as children, have a measurable "state of low arousal in the brain" that may require riskier, more impulsive and higher excitement activities "to achieve the arousal levels that a normally aroused brain typically experiences."

On the "nurture" side of nature/nurture, several studies have found that the environment in which children are raised can have a profound impact on the way their brains process information.

For example, Michaela Chraid, of the University of Bucharest's Faculty of Psychology and Educational Sciences, found that children who are raised in unstable families, including with abusive individuals, can become desensitized to violence at a subconscious level. They often are unaffected emotionally when witnessing horrific acts, such as beheadings, which otherwise disturb children who empathize with the victims.

A family's religious beliefs, although often mentioned in the media as playing a role in sibling terrorist acts, have been falsely implicated, Hanlon said.

Tarsiers are crap at surprise parties
because you can’t tell if they’re actually surprised or not. This is
just kinda how they look.

I’m aware that what I’m about to say may well ignite sectarian conflict within the Star Wars fan community, but I’m pretty sure I know what the inspiration for Yoda was. It wasn’t Albert Einstein, as some heretics have claimed. And the inspiration wasn’t the creator of Yoda himself, as the man who created Yoda has claimed. It was a tiny, wide-eyed, positively adorable primate that bounds around the forests of Indonesia and the Philippines and Borneo: the tarsier.

I have that on good authority. One of the world’s foremost experts on the critter, Myron Shekelle, told me so. And he’s trying to confirm as much. “I work closely with a guy who knows Harrison Ford, and Harrison Ford of course knows Lucas, so we’ve been trying to get the actual answer for a while,” he laughed. “But we don’t have it really confirmed.” Check this article again in a year or so, though, and I could well have added an update with good news from Shekelle.

These are trifles, though. The tarsier (of which there are believed to be around 10 species) is surely one of the most remarkable primates around, with its humongous eyes and long padded fingers and general oh-criminy-did-I-leave-the-oven-on appearance. It can rotate its head like an owl. It speaks in ultrasound. It’s the only primate to feed exclusively on meat. And it’s the only primate to jump right into my heart.

So let’s talk about those eyeballs first, shall we? They’re some of the biggest eyes relative to body size in the animal kingdom, and for good reason: The tarsier is a nocturnal hunter. But we primates, we’re not too good at seeing at night. That’s because almost all primates lack the tapetum lucidum, a reflective tissue in the eyes that greatly enhances night vision for nocturnal creatures. Shine a flashlight in a raccoon’s eyes, for instance, and that evil glow you get back is the tapetum lucidum. You and me, we don’t have this. That’s why our night vision kinda sucks.

An incredible shot of a tarsier coming in
for the kill. With those super-elongated legs, it can bound 15 feet,
landing right on its target.

The tarsier is no exception—well, until it evolved the most glorious peepers a primate could ask for. It took what should be diurnal eyeballs—that is, eyes that only work well in the daytime—and modified them into nocturnal ones, all without the tapetum lucidum layer. “It turns out when you take a diurnal eye and you try and get it to become nocturnal, because it no longer has that layer it has to blow up quite a bit larger in order to collect enough light to really be operative,” said Shekelle.

And boy did they get big. So big, in fact, that the tarsier can’t move them around. But for that it has a solution: It can swivel its noodle almost 360 degrees, Exorcist-style. And with giant eyes and a pivoting noggin, the tarsier is essentially the owl of the rainforest. Two unrelated species arriving at adaptations independently like this is known as convergent evolution—think bats and birds both evolving to fly, one with feathers and the other with a stretchy membrane.

And like an owl, the tarsier is a master nighttime hunter, a menace to creatures like insects and lizards that are under the mistaken impression that the darkness will save them. To target its prey, it uses both its huge eyes and its individually pivoting ears. (Interestingly, around 20 percent of humans can wiggle their ears a little bit because long ago our ancestors could pivot them like tarsiers and cats. If you can do it, that doesn’t mean you’re less evolved. It just means you’re a freak. ¯\_(ツ)_/¯) And it can leap perhaps as far as 15 feet—not too shabby for a creature that would fit in the palm of your hand—thanks to the longest legs relative to body size among primates. Tarsiers are in fact named after their highly elongated tarsus, or the group of bones that make up your ankle and upper foot.

A tarsier’s eyes have evolved to be so
enormous, it can’t even move them in its head. Which means you can say
whatever you want to a tarsier and it can’t roll its eyes at you.

This gives the tarsier a whole lot of spring in its step, bounding from tree to tree like a ricocheting bullet (seriously, check out the video below), landing right on its doomed prey and snagging it with those big hands. Their chompers are really long sharp cones, “so they become like lances, and those are used to just pierce down through the exoskeleton of insects and to deliver one really quick killing bite,” taking care to close its big, beautiful eyes so the struggling prey doesn’t poke them out, said Shekelle. The tarsier is so specialized for this kind of hunting that it doesn’t need to supplement its diet with fruits and veggies like a chimp might, making it the only purely carnivorous primate on Earth.

Also a bit weird for a primate is that some tarsier species don’t seem to be social. Well, all sexually reproducing animals have to be social to some degree so they can get together to mate, so it’d be more accurate to say that they aren’t particularly gregarious, living instead a solitary life. But they have a clever way to find each other and initiate sexy time, all while avoiding detection by their own predators: They can belt out tunes that are far too high-pitched for other creatures to pick up.

It seems the scientists who discovered this had noticed that tarsiers will often stare around with their mouths agape, as if they’re about to scream. Yet nothing comes out. So on a hunch the researchers pointed a device normally used to detect bat echolocation at the tarsiers. And sure enough, the tiny creatures are babbling in frequencies far outside of what our own ears can detect, a unique trait among primates. Being able to hear such noises could also allow them to pick up the ultrasonic calls of their prey, while another hypothesis “is that they basically have a silent alarm that the other animals can’t hear,” said Shekelle.

So we then should ask: If a tarsier screams in the forest, and no one is there to hear it, does it make a sound?

Trouble for the Tarsiers

Sadly, this remarkable strategy does them little good against their greatest enemy: us. Tarsiers are in serious trouble. Deforestation, overhunting, presticides, you name it. The crummy things we’re doing to this planet are hitting the tarsiers hard.

Shekelle has spent years campaigning for the tarsier, making the rounds in its habitats in Southeast Asia to educate locals on conservation. Perhaps the most ironic problem seems to be its villainization as an agricultural pest. “So one of the things that I’ve done is try to work with [farmers] and explain: No no, tarsiers are actually interesting. They’re the only primate that doesn’t eat any plant matter, none at all,” said Shekelle. “If you see them in your crops, they’re eating insects that eat the leaves on your crops, so they’re actually good.”

His advice isn’t always heeded, though. “One very memorable time, after we did this and the people were like, ‘Yeah, yeah that’s very interesting,’ we came back the next day and the guy had cut down his own fruit tree that had the tarsier nest in it. Clearly he didn’t believe a word that we said.”

Jan 8, 2015

The first people who migrated to the Americas did not bring their dogs with them, suggests a new study that concludes dogs likely first came to the Americas only about 10,000 years ago.

If the new research holds true, then the first successful dog migrations to the Americas post-dated the first human migrations by thousands of years. The findings are published in the Journal of Human Evolution.

“Dogs are one of the earliest organisms to have migrated with humans to every continent, and I think that says a lot about the relationship dogs have had with humans,” project leader Kelsey Witt of the University of Illinois said in a press release. “They can be a powerful tool when you’re looking at how human populations have moved around over time.”

Witt and her team studied genetic characteristics of 84 sets of ancient dog remains from more than a dozen sites in both North and South America. The study, according to its authors, represents the largest ever analysis of ancient dogs in the Americas.

The data gathered so far on mitochondrial DNA, which is inherited only from mothers, indicates that dogs have a shorter history in the Americas than was previously suspected.

“Dog genetic diversity in the Americas may date back to only about 10,000 years ago,” Witt explained.

“This also is about the same time as the oldest dog burial found in the Americas,” her colleague Ripan Malhi added. “This may not be a coincidence.”

In some samples, the team found significant genetic similarities with American wolves, suggesting that some of the dogs interbred with, or were domesticated anew, from American wolves.

The study also presents intriguing clues as to what life was like for these earliest American dogs, including how humans valued them.

A site called Janey B. Goode near what is now St. Louis, MO, used to be where the ancient city of Cahokia was located. Cahokia was the largest and first known metropolitan area in North America. It was bustling about 1,000 years ago.

The researchers note that dozens of dogs were ceremonially buried at Janey B. Goode then, suggesting that people there had a special reverence for dogs. While most of the dogs were buried individually, some were placed back-to-back in pairs. The meaning of this remains a mystery for now.

On the downside, at least from a dog’s perspective, canine remains were also found with food debris from Cahokia, strongly suggesting that people there consumed dogs for dinner from time to time.

The study also found that there was greater ancient dog diversity in the Americas than previously thought. The researchers, however, found unusually low genetic diversity in some dog populations, suggesting that humans in those regions may have engaged in dog breeding.

Tilda, a female orangutan at the Cologne Zoo in Germany, appears to have figured out that if she communicates like a person, she can better grab the attention of zookeepers.

She is the first wild-born Bornean orangutan known to produce novel human-like vocalizations, according to a paper published in PLOS ONE. She is also the only wild born orangutan that can whistle tunes, just as humans do.

Tilda's background is somewhat of a mystery, but it's suspected that as a youngster, she was a circus animal.

"It is our belief that Tilda learned to produce these calls from humans while she was in the entertainment business, putatively by copying a human trainer," lead author Adriano Lameira of the University of Amsterdam's Institute for Biodiversity and Ecosystem Dynamics, told Discovery News. Tilda is now producing the calls all on her own without prompting, and with a specific goal in mind.

Lameira and his team came to these conclusions after making video and audio recordings of Tilda and then analyzing her communications. Two of her calls are unknown among other orangutans and show human-like characteristics, the researchers conclude.

For one call, Tilda clicks her tongue to produce different tones, just as a human can. The process she goes through to make the sounds is comparable to a human producing voiceless consonants, such as saying the letters "p," "k" and "t."

For the other call, Tilda grumbles in a way that's comparable to humans producing vowel sounds. Both calls require that she rapidly open and close her mouth in rhythms similar to those of human speech.

The meaning of her calls is clear, because she often claps or extends her index finger towards food in the caretakers' hands as she vocalizes.

"They are what we would call attention gathering or come-hither calls, which indeed are mostly used when the human caretakers are handling food," Lameira said. "I would translate them into, 'Come here and give that food to me!"

Aside from revealing Tilda's cleverness, the findings suggest that the common ancestor of great apes possessed the capacity to learn and produce both vowel and consonant-based calls. This is supported by studies on other primates.

Lameira said that in the wild, orangutans create their own "call cultures," where different populations produce their own unique vocalizations.

"The notion that great ape calls are hard-wired and inflexible is likely an artifact of our very poor understanding of the call communication of these species, rather than that their calls are factually hard-wired or inflexible," Lameira added.

Tilda might meet her match in another adult orangutan, Bonnie.

"Bonnie, a female orangutan at the National Zoo in DC, taught herself to whistle for what seems simply to be the pleasure of it, though there's no whistling known to be part of the call system of any wild apes," Mark Sicoli of Georgetown University's Department of Linguistics told Discovery News.

Researchers in Sri Lanka's Uda Walawe National Park have documented and recorded on video not only a male dwarf Asian elephant but also that selfsame creature appearing to get the better of a much larger, full-sized male in a jousting session.

The plucky elephant -- dubbed the Walawe Dwarf by its observers -- was just 6.6 feet tall (2 meters) and represented the first confirmed evidence of dwarfism in an Asian elephant, BBC Earth reported. The research was led by Shermin de Silva, director of the Uda Walawe Elephant Research Project.

The elephant, whose shortened limbs are probably the result of a genetic mutation, was first seen in the park in 2012 and again in 2013 by de Silva and other research teams. In 2014, her team witnessed the encounter with the larger foe, documented in a paper published in BioMed Central last month.

The researchers did not see the culmination of the tussle between the large and small elephants, but in the video above, it's pretty clear that the dwarf did not seem at all intimidated.

What's more, the Walawe Dwarf was seen just two days later, resting, so it had not been harmed in the encounter. The special elephant is about 30 to 35 years old, an expert told BBC Earth.

A rare wall relief showing an unidentified pharaoh has been discovered within the sandstone quarries of Gebel el Sisila, north of Aswan.

Carved into the vertical face of the quarry wall, some 5 feet above the ground, the stela depicts the pharaoh presenting offerings to Thoth, the ancient god of wisdom, and Amun-Ra, the king among gods.

She added the three figures are rather poorly preserved, although some details can be made out.

“We can see the characteristic double feather crown of Amun-Ra, and the moon disc of the ibis-headed Thoth,” Nilsson said. “Unfortunately, the item presented by the pharaoh is no longer discernible.”

Preliminary study suggests the stela dates to the late dynastic period, perhaps the Third Intermediate Period, which began with the death of pharaoh Ramesses XI in 1070 B.C. and ended with the foundation of the Twenty-Sixth Dynasty by Psamtik I in 664 BC.

Readable inscriptions on the stela are merely titles of the gods, “Amun-Ra, King of the Gods, Lord of (-)”, and “Thoth, Twice Great, Lord of (-)”.

Just below the winged solar disc of the pharaoh, adorned with two uraei (stylized Egyptian cobras symbols of royalty and deity) the text reads: “Lord of the Two Lands, Behedet (Horus of Edfu).”

The personal text of the pharaoh is limited to “Lord of the Two Lands” followed by a poorly preserved cartouche and a short epithet.

“The team is currently trying to retrieve more information, but the area of the figure and title of the pharaoh is eroded by wind and sand, not to mention a natural fracture in the rock,” Nilsson said.

The finding is the result of an epigraphic and archaeological survey mission of Lund University, Sweden, that has studied the site since early 2014.

The researchers have discovered more than 60 rock art sites on both sides of the Nile that date from the Epipalaeolithic (about 8500 to 6500 B.C.), Predynastic (about 4000-3100 B.C.), and Early Dynastic (about 3100-2686 B.C.) periods.

Jan 7, 2015

The gateways of an ancient Roman fort in Britain are roughly aligned with the light from the sun during the summer and winter solstices — a design that would have resulted in a striking scene on the shortest and longest days of the year, a researcher says.

The fort had four gateways facing one another. During the summer solstice, the sun would rise in alignment with the fort's northeastern and southwestern gates, and set in alignment with its northwestern and southeastern gates, the researcher reported in the new study.

During the winter solstice, the sun would rise in line with the fort's southeastern and northwestern gates, and set in line with the fort's southwestern and northeastern gates.

"Moreover, the four towers of the garrison seem aligned to cardinal directions," Amelia Carolina Sparavigna, a physics professor at the Politecnico di Torino (Polytechnic University of Turin) in Italy, wrote in the study, published Dec. 17 in the journal Philica.

The fort's ruins are located near Hardknott Pass in Cumbria, England, and offer a commanding view of the sprawling Eskdale Valley. Built during the reign of Emperor Hadrian, who ruled from A.D. 117 to 138, the structure was part of a series of fortifications that once guarded the Roman frontier in Britain.

Sparavigna used online software to calculate the angles at which the solstice sun rises and sets at the fort. She then used satellite maps available on Google Earth to determine how the rising and setting solstice sun compares to the fort's features.

"This image is very interesting, because we can easily imagine the sun passing through the four gates on solstices," Sparavigna said.

he summer solstice (which last occurred on June 21, 2014) represents the longest day of the year, when the sun appears at its highest point in the sky. The winter solstice (which last occurred on Dec. 21, 2014) represents the shortest day of the year, when the sun appears at its lowest point in the sky.

But the reason for the fort's celestial alignment remains unclear. In her paper, and in an email to Live Science, Sparavigna noted that she is not an expert on Roman religion. However, she did offer some ideas that might help to explain the alignment.

"An orientation of sacred places to sun and sky is common to several religions," Sparavigna told Live Science in an email. It is "quite possible that the Hardknott fort has a symbolic homage to the sun," she said. "The god could be Sol, the ancient Roman god of the sun, which evolved Sol Invictus (a deity whose name means "unconquered sun")."

At least 12 people were killed when gunmen armed with Kalashnikovs and a rocket-launcher opened fire in the offices of French satirical weekly Charlie Hebdo on Wednesday, said sources close to the investigation.

It was not yet clear how many had been injured.

Deputy Mayor of Paris Bruno Julliard earlier said "six people are seriously injured," including a policeman. It was not clear whether these now figured among the dead.

French President Francois Hollande arrived at the scene of the shooting after rushing there and calling an emergency cabinet meeting, the presidency said.

The government raised its alert level to the highest possible in the greater Paris region.

A source close to the investigation said two men "armed with a Kalashnikov and a rocket-launcher" stormed the building in central Paris and "fire was exchanged with security forces."

The source said a gunman had hijacked a car and knocked over a pedestrian while attempting to speed away.

The publication's cartoonist Renaud Luzier earlier told AFP there were "casualties" after the incident.

The satirical newspaper gained notoriety in February 2006 when it reprinted cartoons of the Prophet Mohammed that had originally appeared in Danish daily Jyllands-Posten, causing fury across the Muslim world.

Its offices were fire-bombed in November 2011 when it published a cartoon of Mohammed and under the title "Charia Hebdo."

Despite being taken to court under anti-racism laws, the weekly continued to publish controversial cartoons of the Muslim prophet.

In September 2012 Charlie Hebdo published cartoons of a naked Mohammed as violent protests were taking place in several countries over a low-budget film, titled "Innocence of Muslims," which was made in the United States and insulted the prophet.

French schools, consulates and cultural centers in 20 Muslim countries were briefly closed along with embassies for fear of retaliatory attacks at the time.

Editor Stephane Charbonnier has received death threats and lives under police protection.

NASA's Kepler spacecraft has discovered its 1,000th alien planet, further cementing the prolific exoplanet-hunting mission's status as a space-science legend.

Kepler reached the milestone today (Jan. 6) with the announcement of eight newly confirmed exoplanets, bringing the mission's current alien world tally to 1,004. Kepler has found more than half of all known exoplanets to date, and the numbers will keep rolling in: The telescope has also spotted 3,200 additional planet candidates, and about 90 percent of them should end up being confirmed, mission scientists say.

Furthermore, a number of these future finds are likely to be small, rocky worlds with temperate, relatively hospitable surface conditions — in other worlds, planets a lot like Earth. (In fact, at least two of the newly confirmed eight Kepler planets — which were announced in Seattle today during the annual winter meeting of the American Astronomical Society — appear to meet that description, mission team members said.)

"Kepler was designed to find these Earth analogues, and we always knew that the most interesting results would come at the end," Kepler mission scientist Natalie Batalha, of NASA's Ames Research Center in Moffett Field, California, told Space.com last month.

"So we're just kind of ramping up toward those most interesting results," she added. "There's still a lot of good science to come out of Kepler."Changing the Game

Exoplanet science is a young field. The first world beyond our solar system wasn't confirmed until 1992, and astronomers first found alien planets around a sunlike star in 1995.

The Kepler spacecraft has therefore been a revelation, and has helped lead a revolution. The $600 million mission launched in March 2009, with the aim of determining how frequently Earth-like planets occur around the Milky Way galaxy.

The telescope spots alien planets using the "transit method," watching for the telltale brightness dips caused when an orbiting planet crosses the face of its host star from Kepler's perspective.

The instrument generally needs to observe multiple transits to flag a planet candidate, which is part of the reason why the most intriguing finds are expected to come relatively late in the mission. (Several transits of a huge, close-orbiting "hot Jupiter," which has no potential to host life, can be observed relatively quickly, while it may take years to gather the required data for a more distantly orbiting, possibly Earth-like world.)

"Before, we were just kind of plucking the low-hanging fruit, and now we're getting down into the weeds, and things are getting a little harder," Batalha said. "But that's a challenge we knew we would have."

Kepler candidates must then be confirmed —by follow-up observations using other instruments, for example, or by rigorous analysis of the Kepler dataset.

That enormous dataset has allowed researchers to study alien planets in new systematic and statistical ways. In 2013, for example, two different studies used Kepler data to estimate the percentage of red dwarfs — stars smaller and dimmer than the sun — that host Earth-size planets in their "habitable zone" (the range of distances from a star that could support the existence of liquid water).

One study put the number at 15 percent, while the other calculated 40 percent. Even the lower estimate should cheer astrobiologists, for red dwarfs are the most common stars in the Milky Way, making up about 70 percent of the galaxy's 100 billion or so stars.

Kepler has not yet discovered a true Earth twin — an Earth-size planet in the habitable zone of a sunlike star — but the mission is on track to figure out just how commonly these worlds occur throughout the galaxy, Batalha said.

"I don't yet have a good sense of the completeness of the habitable zone; it could be that we will be sensitive toward the inner half of the habitable zone, maybe not the complete habitable zone," she said. "But I am confident now that we are going to get a number based on actual discoveries, and that we are not going to have to rely on extrapolation."A New Mission

Kepler's original planet-hunting campaign, which was designed to last for 3.5 years, called for the spacecraft to continuously monitor about 150,000 distant stars in the constellations Lyra and Cygnus.

The data-gathering part of that mission came to an end in May 2013, when the second of Kepler's four orientation-maintaining reaction wheels failed, robbing the spacecraft of its super-precise pointing ability. A repair mission is not going to happen; Kepler orbits the sun, not the Earth.

But Kepler is still observing the heavens. In May 2014, NASA approved a new two-year mission extension called K2 for the space observatory, during which a compromised Kepler continues to hunt for exoplanets but also observes other cosmic objects and phenomena, including supernova explosions and star clusters.

K2 should spot a number of relatively nearby exoplanets that can be observed in detail by NASA's $8.8 billion James Webb Space Telescope (JWST), which is scheduled to launch in late 2018, Batalha said.

"So we will be well-poised when JWST launches to begin studying the diversity of the atmospheres of planets, thanks to discoveries made by K2," she said. (NASA's Transiting Exoplanet Survey Satellite, or TESS, scheduled to launch in 2017, should also find a number of promising targets for follow-up work by JWST, researchers say.)

While K2 observations continue, Batalha and other Kepler scientists are still busy analyzing data from the prime mission. NASA wants this work done by September 2017, and the team should meet that deadline, Batalha said.

"Sometime around September of 2016, we'll probably have our final catalog," she said. "And then between September and January [of 2017], we'll be producing the products that will allow people to do the statistics with the catalog. And then we'll kind of write up all of our documentation and final papers, and turn off the lights and go home sometime around the end of summer 2017."

SETI has pointed a powerful radio telescope array at the Kepler Space Telescope’s most recent exoplanetary discovery in the hope of detecting an artificially-generated radio signal. Alas, the world is not transmitting, and probably isn’t home to an extraterrestrial intelligence.

SETI, which stands for the Search for Extraterrestrial Intelligence, utilized the Allen Telescope Array (ATA), located in at Hat Creek Radio Observatory, 290 miles northeast of San Francisco, Calif., to study HIP 116454b, an exoplanet 180 light-years away in the constellation Pisces. The exoplanet, that measures 2.5 times the diameter of Earth (and is therefore defined as a ‘super-Earth’), was the first discovery made by Kepler in its rebooted “K2″ mission.

During its primary mission, the Kepler suffered the breakdown of its second reaction wheel in May 2013. The loss of stability forced Kepler into an early retirement. Fortunately, NASA engineers were able to think up an ingenious new mission profile that requires only two of the four reaction wheels to be operational. And in December, K2′s first exoplanet discovery was announced: HIP 116454b.

HIP 116454b isn’t, however, what we would consider to be ‘habitable’ in any way. The super-Earth has a rapid 9-day orbit around its host star and is therefore expected to be a roasted world, probably tidally locked (i.e. with one hemisphere of the exoplanet constantly facing its star).

Why would SETI bother aiming the ATA at this unlikely target, searching for radio signals from a hypothetical alien civilization?

“…as centuries of experience have shown, observation sometimes trumps expectation, and that is why new exoplanets — whether they seem promising for life or not — are routinely observed by the SETI Institute with the Allen Telescope Array,” writes SETI Institute Senior Astronomer and Director Seth Shostak.

In other words, just because we deem a planet too harsh for “life as we know it” to evolve, science has this wonderful habit for turning up results we didn’t expect — so why not listen in on HIP 116454b?

Historically, SETI has listened focused distant stars in the hope of detecting narrow-band radio signals from technologically-advanced extraterrestrials. The logic is that humanity is constantly leaking radio signals into space, and we consider ourselves to be at least technologically proficient, so if we can detect similar signals from another star system, perhaps there’s another civilization out there at a similar state of technological can-do as us.

On May 6, 1910, Halley’s comet approached Earth and killed England’s King Edward VII, according to some superstitious folk. No one could definitively say how it did, but it certainly did. And that wasn’t its only offense. The Brits also figured it was an omen of a coming invasion by the Germans, while the French reckoned it was responsible for flooding the Seine.

Yet there was even more apocalyptic hype surrounding the 1910 return of Halley’s comet, which is named for astronomer Edmond Halley, who calculated that the celestial body would appear on average every 76 years. Writing to the Royal Observatory, one worrywart warned the comet would “cause the Pacific to change basins with the Atlantic, and the primeval forests of North and South America to be swept by the briny avalanche over the sandy plains of the great Sahara, tumbling over and over with houses, ships, sharks, whales and all sorts of living things in one heterogeneous mass of chaotic confusion.”

Throughout history, there’s always been a bit of panic when comets approached the sun, burning off into long, ominous tails. But in the months preceding Halley’s flyby of Earth on May 19, 1910, folks got real creative with their anxiety. It didn’t help that a few months earlier, The New York Times had announced that one astronomer theorized that the comet would unceremoniously end life as we know it.

French astronomer Camille Flammarion sure knew how to part a head of hair.

He was a Frenchman named Camille Flammarion, and in typical French despair, he reckoned that as we passed through the comet’s tail, “cyanogen gas would impregnate the atmosphere and possibly snuff out all life on the planet,” The Times reported. Astronomers had detected the cyanogen in the tail using spectroscopy, which reveals an object’s composition by analyzing the light coming off it. “Cyanogen is a very deadly poison, a grain of its potassium salt touched to the tongue being sufficient to cause instant death,” the paper wrote. To its credit, though, The Times noted that most astronomers did not agree with Flammarion.

One skeptic was Percival Lowell, who noted the gas was “so rarefied as to be thinner than any vacuum,” and therefore posed no threat. Also stepping in was Robert Ball, director of the Cambridge Observatory, who noted that another famed astronomer, John Herschel, reckoned “the whole comet could be squeezed into a portmanteau.” In a hilarious response to the question of whether a comet should be shoved in a suitcase (turns out it’s actually 9 miles long), The New York Times hit back with a short piece that begins with a vocabulary lesson:

“The rising generation hereabout may need to be told that ‘portmanteau’ is a word of French origin used in England to describe the useful article called in vulgar American circles a ‘grip,’ and among the truly cultured a ‘suitcase.’

“If Sir John Herschel really said this comet could be packed in a suitcase (Sir Robert is not quite sure that the hyperbolical remark originated with Herschel), he was talking nonsense. The proposition suggests three factors—the comet, the suitcase, and the packer. The comet will soon be visible, and there are plenty of suitcases, but who will undertake the packing? We do not believe that comet could be packed into a suitcase. Experience teaches that mighty little can be packed in a suitcase by any man. It takes a woman to pack one properly. There are plenty of women, of course, but Sir John’s lighthearted assertion, now gayly step-fathered by Sir Robert, will not tempt them to do any unnecessary packing. A comet, once packed in a suitcase, or even in a trunk of the largest size, would be mussed beyond recognition and of no further use to anybody. Better leave the comet where it is. We shall all feel safer.”

Halley’s comet, as seen in its 1986 pass by Earth. And it didn’t even end the world…yet.

Others also adopted a jovial outlook for the comet’s approach. “Tunesmiths composed songs to serenade the heavenly visitor, and poets burst into verse,” writes Ian Ridpath in A Comet Called Halley. “Products such as Bird’s Custard and Pears’ Soap featured the comet in their advertising: ‘Pears’ soap is visible day and night all over the world’ was one slogan.”

But other enterprising capitalists hatched more nefarious schemes. Fraudsters hawked anti-comet pills, with one brand promising to be “an elixir for escaping the wrath of the heavens,” while a voodoo doctor in Haiti was said to be selling pills “as fast as he can make them.” Two Texan charlatans were arrested for marketing sugar pills as the cure-all for all things comet, but police released them when customers demanded their freedom. Gas masks, too, flew off the shelves.

The spokesman for Hope’s completely worthless anti-comet pills was apparently a hobo.

It’s little wonder, then, that some people were getting a tad riled up. Writes Ridpath: “A shepherd in Washington State was reported to have gone insane with worry about the comet, while in California a prospector nailed his feet and one hand to a cross and, despite his agony, pleaded with rescuers to let him remain there.” Churches found themselves packed to the brim with worried followers, while at home people were going so far as to plug up keyholes to keep out the comet’s vapors. (Sound familiar? If you think these people were nuts, remember that in 2003 our government told us to seal our homes with duct tape in the event of a terrorist attack. In 2003. The 21st century.)

More rational humans saw the comet for what it really was: A truly spectacular event that a lot of us see but once in a lifetime. As Earth passed through the comet’s tail on May 19, 1910, curious onlookers packed rooftops around the world, while the French—other than Flammarion, presumably—enjoyed special comet dinners. Indeed, Flammarion seemed to stick to his theory right until the end of the comet’s show, claiming that four observers “had certain olfactory experiences, which are described variously as a smell of burning vegetables, or a marsh, or of acetylene.”

Jan 6, 2015

A new way of looking at the history of the Rapa Nui, the civilization that lived on Easter Island, reveals details about how they lived before Europeans arrived on the island in 1722.

It's long been theorized that the Rapa Nui disappeared because they overfarmed their land, leading to widespread starvation and, it's said, maybe even cannibalism.

But a group of scientists from the United States, Chile and New Zealand, writing in the most recent Proceedings of the National Academy of Sciences, found that ancient obsidian artifacts from the island told a different story.

"This analysis demonstrates that the concept of “collapse” is a misleading characterization of prehistoric human population dynamics," the authors wrote in their summary statement.

The researchers dated 286 obsidian artifacts, including farming tools, from three sites on the island, using a method that measures how quickly obsidian absorbs water.

They found that the Rapa Nui population didn't crash before 1722, but rather shifted around the island as rainfall levels affected farming successes. In fact, previous to the arrival of Europeans, the Rapa Nui curtailed farming at two sites that had been successful before, likely because of periods of drought.

After Europeans arrived, the native population didn't immediately decline. In fact, it expanded in some areas, the researchers said. But it was just a matter of time before foreign diseases like smallpox, and the selling of the Rapa Nui into slavery, spelled the end for the builders of the massive, mysterious statues that grace Easter Island today.

If you’re worried about climate change, the recent news that 2014 was the hottest year on record didn’t help your anxiety. But here’s at least one positive bit of news to ease your mind a little. Researchers have discovered that tropical forests -- in reaction to rising atmospheric levels of carbon dioxide -- may be absorbing far more of the greenhouse gas than previously believed.

A NASA-led study, published in Proceedings of the National Academy of Sciences, estimates that tropical forests annually absorb 1.4 billion metric tons of carbon dioxide out of a total global absorption of 2.5 billion metric tons. That’s more than is absorbed by the boreal forest in Canada, Siberia and other northern regions, the researchers say.

“This is good news, because uptake in boreal forests is already slowing, while tropical forests may continue to take up carbon for many years,” lead author David Schimel of NASA’s Jet Propulsion Laboratory, Pasadena, Calif., said in a press release.

The planet’s wooded areas have been a big part of slowing the effects of increased human output of carbon dioxide, a process called sequestration. Trees remove CO2 from the atmosphere during photosynthesis, storing some of it in their wood and leaves, and transferring some to the soil through their roots, as this article from the U.S. Forest Service’s website explains. Forests and other vegetation take care of about 30 percent of human carbon emissions. But if that rate of absorption ever slows, the the rise in global temperature would speed up as a consequence.

For the past quarter-century, climate scientists have believed that the northern forests were sequestering more carbon dioxide than the tropical forests, based upon what was then understood about global air flow, and the belief that massive deforestation in tropical areas was causing those forests to emit more carbon than they were storing. But in the mid-2000s, Britton Stephens of the National Center for Atmospheric Research, who is another of the study’s co-authors, studied measurements made by aircraft and concluded that existing climate models were underestimating tropical forests’ carbon absorption. This new study builds upon that view.

Astronomers have found eight more worlds properly situated from their parent stars for liquid surface water, a condition which, at least on Earth, is believed to be key for life to evolve.

The newly found planets include two that are more similar to Earth than any other exoplanets found to date, astronomers said at a press conference Tuesday at the 225th American Astronomical Society meeting in Seattle, Wash.

“Most of these planets have a good chance of being rocky, like Earth,” astronomer Guillermo Torres, with the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., said in a statement.

Torres and colleagues found the planets by analyzing data collected by NASA’s Kepler space telescope. The Earth-cousins include Kepler-438b, located about 470 light-years away, and Kepler-442b, located about 1,100 light-years from Earth. Kepler-438b has a diameter just 12 percent bigger than Earth and Kepler-442b is one-third larger.

The planets orbit so-called red dwarf stars, which are smaller and cooler than the sun.

“We don’t know for sure whether any of the planets in our sample are truly habitable,” said David Kipping, also with CfA. “All we can say is that they’re promising candidates.”

A computer analysis published last year, however, raises questions about whether red dwarf stars make for life-friendly planets.

The study suggests a planet situated relatively close to a red dwarf star would be pummeled by powerful radioactive stellar winds. Theoretically, only planets with a strong magnetic field or thick atmosphere may be capable of hosting life — at least life as it appears on Earth, physicist Ofer Cohen, also with the Harvard-Smithsonian Center for Astrophysics, told Discovery News last year.

Twenty years ago, the Hubble Space Telescope showed the world what has become one of the most famous images of our time. Staring deep into the Eagle Nebula, Hubble demonstrated its sheer imaging power, picking out the vast pillars of gas and dust in a star-making factory. Deep within their dusty cocoons, baby stars are being born, a factor that spawned the apt moniker “Pillars of Creation.”

I was only 15 when these mind-blowing views from Hubble started appearing in newspapers and magazines, and I remember having a huge poster on my wall of the Pillars that I’d often stare at, looking so hard at the details that I would eventually be frustrated by the pixelated resolution of the printed glossy paper. But now, in this brand new Hubble observation of the same portion of the Eagle Nebula, the harder you stare, it seems like the detail goes on forever.

Released today in celebration of Hubble’s 25th year in space, this version of the Pillars is more detailed than ever before, capturing the finer details over a wider view.

Using data collected by the Wide Field Camera 3 that was installed on Hubble in 2009, additional visible light detail has been added. As a bonus, an additional infrared layer has been released separately, producing an eery version of the Pillars of Creation — the cocooned stars that were once obscured by the opaque dust are suddenly visible:

Revisiting this star-forming region isn’t only great for some mind-blowing photos, it also serves a practical purpose. As one would expect, the Pillars are highly dynamic and astronomers can compare the original observations with this modern version 20 years later. Any rapid motion in the clouds and changing brightness in stars can be detected and analyzed, potentially enriching theoretical star formation models.

But for me, staring into the Pillars once more reminds me of my childhood fascination with the birth of stars within a nebula, the very definition of creation occurring only 6,500 light-years from Earth. This is where stars are born, eventually giving birth to systems of alien worlds and, in millions to billions of years time, possibly life.

An ancient, two-sided amulet uncovered in Cyprus contains a 59-letter inscription that reads the same backward as it does forward.

Archaeologists discovered the amulet, which is roughly 1,500 years old, at the ancient city of Nea Paphos in southwest Cyprus.

One side of the amulet has several images, including a bandaged mummy (likely representing the Egyptian god Osiris) lying on a boat and an image of Harpocrates, the god of silence, who is shown sitting on a stool while holding his right hand up to his lips. Strangely, the amulet also displays a mythical dog-headed creature called a cynocephalus, which is shown holding a paw up to its lips, as if mimicking Harpocrates' gesture.

On the other side of the amulet is an inscription, written in Greek, that reads the same backward as it does forward, making it a palindrome. It reads:

ΙΑΕW

ΒΑΦΡΕΝΕΜ

ΟΥΝΟΘΙΛΑΡΙ

ΚΝΙΦΙΑΕΥΕ

ΑΙΦΙΝΚΙΡΑΛ

ΙΘΟΝΥΟΜΕ

ΝΕΡΦΑΒW

ΕΑΙ

This translates to "Iahweh(a god)is the bearer of the secret name, the lion of Re secure in his shrine."

Researchershave found similar palindromes elsewhere in the ancient world writes Joachim Sliwa, a professor at the Institute of Archaeology at Jagiellonian University in Kraków, Poland, in an article recently published in the journal Studies in Ancient Art and Civilization.

Sliwa notes that the scribe made two small mistakes when writing this palindrome, in two instances writing a "ρ" instead of "v."

The amulet was discovered in the summer of 2011 by archaeologists with the Paphos Agora Project. Led by Jagiellonian University professor Ewdoksia Papuci-Wladyka, this team is excavating an ancient agora at Nea Paphos, and uncovered this amulet during their work. Agoras served as gathering places in the ancient world.

Amulets like the one found at Nea Paphos were made to protect their owners from danger and harm, Papuci-Wladyka told Live Science in an email.

Christians and pagans

During the 5th and 6th centuries, Cyprus was part of the Eastern Roman Empire. The Roman Empire had split in two during the 4th century, with Cyprus falling under control of the east. When the Western Roman Empire fell during the 5th century, the Eastern Roman Empire continued to flourish and became what is sometimes called the Byzantine Empire.

By the 5th century, Christianity was the official religion of the Eastern Roman Empire, and as time went on, traditional polytheistic (also called pagan) practices came under tighter restrictions and bans. Nevertheless, some people continued to practice the old beliefs, worshipping the traditional gods.

This amulet adds to evidence that people practiced traditional, polytheistic beliefs on Cyprus for an extended time, Papuci-Wladyka said. She notes that a structure called the Villa of Theseus has a mosaic with pagan elements that was likely repaired as late as the 7th century A.D.

It "rather seems that Christian and pagan religions coexisted in Paphos in times of amulet being in use," Papuci-Wladyka told Live Science in an email.Strange iconography

Despite that coexistence, the amulet has several unusual features that suggest its creator didn't fully understand the mythological characters depicted.

"It must be stated that the depiction is fairly unskilled and schematic. It is iconographically based on Egyptian sources, but these sources were not fully understood by the creator of the amulet," Sliwa wrote in the journal article.

Deep in the forests of northwestern Europe, the ghosts of battle from World War II remain. These landscapes preserve troves of bomb craters, trenches and even the remains of supply depots — all of which have not been well studied until now.

These battleground remnants may shed new light on logistical support of German field armies and the impact of Allied bombings, researchers said in a new study.

David Passmore, a geoarchaeologist and lecturer at the University of Toronto, Mississauga, led the study. Passmore specializes in conflict archaeology, the study of battlefields and conflict in human societies.

"Although the history of the Second World War is widely documented and intensely researched, the archaeology of WWII has only recently begun to be formally investigated," Passmore told Live Science.

Forest battle scars

There have been plenty of studies on coastal fortifications, large battlefields and the D-Day landings, but Passmore couldn't find any documentation of conflict in the forests of Europe.

"We realized quite soon there had been very little formal study of WWII landscapes in these forested terrains," he said.

So, Passmore and his colleagues conducted a formal archaeological survey of key WWII battlegrounds from June 1944 through February 1945. In particular, the archaeologists focused on parts of northwestern France; the Ardennes forests of Belgium, Luxembourg and Germany; the Hürtgenwald and Reichswald forests of western Germany; and the woodlands around the Arnhem region of the Netherlands.

They conducted field walks of these areas based on information from academic studies, Internet searches and WWII heritage guidebooks. The researchers found evidence of bomb craters, foxholes and trenches, as well as German logistics depots.

These landscapes "can tell us a great deal," Passmore said. "These things illuminate war diaries and accounts of battlefield history, and provide a far more accurate impression of where troops were fighting, how they were fighting" and so on, he said.

What the Allies knew

The logistics depots provide a picture of exactly where and how the Germans established their support network for armies before the Allied invasion of Normandy, how they developed this network during the invasion and how the depots were overrun, Passmore said.

"We are now interested in investigating what the Allies knew of these depots, and how they went about attacking them with bomber forces," he said. By comparing Allied intelligence records of the suspected locations of German depots to the archaeological evidence, researchers can determine how successful the Allied bombings were.

After carefully measuring the masses of small, rocky exoplanets, astronomers have come to the conclusion that our solar system may not be unique and, by extension, those exoplanets surveyed are likely composed of similar materials as Earth.

Using the High-Accuracy Radial velocity Planet Searcher (HARPS) North instrument on the 3.6-meter Telescopio Nazionale Galileo in the Canary Islands, the researchers, led by Courtney Dressing of the Harvard-Smithsonian Center for Astrophysics (CfA), focused on the slight wobble small exoplanets exert on their host stars.

As an exoplanet orbits its star, the tiny gravitational pull can tug the star slightly off-center. By measuring this ‘wobble’ (through the analysis of the shifting of wavelength of the detected starlight), astronomers are able to determine the mass of that exoplanet. This mode of exoplanet detection is known as the “radial velocity” method. By combining these mass measurements with observations made by NASA’s Kepler Space Telescope, which uses the “transit method” to detect exoplanets and determine their physical size, the density of that exoplanet can be calculated. With this valuable information, scientists can begin to understand what that world is made of.

In a new study presented today (Jan. 5) at the 225th American Astronomical Society meeting in Seattle, Wash., and accepted for publication in the The Astrophysical Journal, Dressing’s team discussed their findings for small worlds that have a lot more in common with Earth than we thought.

“Our strategy for using HARPS-North over the past year has been to focus on planets less than two times the diameter of Earth and to study a few planets really well,” said astronomer David Charbonneau, also of the CfA and head of the HARPS-North Science Team.

One key discovery focused on Kepler-93b, an exoplanet identified by Kepler. It is known to be 1.5 times the size of Earth, but it has an extreme 4.7-day orbit around its host star. Before Dressing’s team began measurements of the distant world, very little was known about its mass and composition. But HARPS-North was able to precisely measure its mass to 4.02 times the mass of Earth. From this information alone, the astronomers could say that this world was a rocky exoplanet.

Then, the astronomers measured the densities of “all ten known exoplanets with a diameter less than 2.7 times Earth’s,” according to a CfA press release, and found that five of those worlds with diameters less than 1.6 times that of Earth showed a very tight relationship between mass and size. Most interestingly, both Earth and Venus, when added to the analysis, fitted neatly into the same correlation.

Keeping accurate time and determining age are two crucial, constant goals in science. In the 1700s the proof and construction of an elegant, precise maritime clock opened up much safer and more efficient ocean exploration and provided a way forward for more accurate mapping on Earth. Before then, mariners and astronomers alike were both, literally, at sea.

Likewise, until now, determining the age of stars has been equivalent only to saying that a person is young or old, and our guesses of someone’s age are typically off by as much as 15 percent. But by building on the work of others (as it goes in science) and carefully working out for over a decade how to construct a “clock” to measure the ages of stars, Sydney Barnes, of the Leibniz-Institut fuer Astophysik Potsdam (AIP), Germany, derived an elegant and extraordinary method he named “gyrochronology” to derive a star’s age from its spin rate and its mass.

Barnes named his method from the Greek “gyros” which equals rotation, “chronos” which means time and “logos” for study.

“We here develop an improved way of using a rotating star as a clock, set it using the sun and demonstrate that it keeps time well,” wrote Barnes in 2007 (PDF), but his work on this groundbreaking theory goes back to 2000.

Now, in a new study published in the journal Nature and announced today at the 225th American Astronomical Society meeting in Seattle, Barnes and his colleagues have measured more than 20 sun-like stars believed to have identical ages, all belonging to a single a star cluster, and by showing that gyrochronology gives an age of 2.5 billion years for all of them to within 10 percent, have essentially proven the method beyond reasonable doubt.

“In fact, the uncertainty on the gyro-age of the cluster as a whole is two percent, which means that the new clock is now more precise than the ones used to set it,” said Barnes.

The study’s team, led by Soren Meibom, of the Harvard-Smithsonian Center for Astrophysics, in Cambridge, Mass., used NASA’s Kepler Space Telescope to measure the tiny variations of starlight over days or weeks that are caused as dark spots on the surfaces of the stars are alternately revealed and hidden by the rotation.

These space telescope measurements represent the culmination of a hard slog for over a decade by Meibom, Barnes and the other co-authors using ground-based telescopes to acquire and analyze the required support observations, to develop the theoretical framework adequately and to measure and interpret other appropriate clusters for possible deviations.

Among other crucial things, this work ensures that all the stars measured are indeed cluster members and that their interpretation resides securely within a framework that works for all other current knowledge about rotating stars.

“We have found that the relationship between mass, rotation rate and age is now defined well enough by observations -- and is sufficiently supported by the theory -- that it is possible to obtain the ages of non-cluster stars to within 10 percent,” said Barnes.

In the scientific race of the 1770s to determine longitude at sea, John Harrison designed and constructed a maritime clock that pinpointed longitude to within one half of a degree. Similarly, using the mathematical clock of gyrochronology, combined with state-of-the-art measurements from the Kepler Space Telescope and hard work from ground-based ones, this science team has made a quantum leap in accurately determining ages of stars.

“Now we can look at a random cool star on the sky and use the best gyrochronology models to get its age,” said Meibom.

“This means that precise ages can be derived for large numbers of cool field stars in our galaxy,” added Barnes.

Gyrochronology ushers in a new era in astronomy and astrophysics by enabling a better understanding of the chronologies of astronomical phenomena and how our galaxy was assembled over time. It could also help in selecting which planets to target in the search for ‘exo-life.’

But, like the stars it measures, gyrochronology is interesting a priori. An outline history of how this fundamental method was derived is also an unknown but compelling story. To this author it is a modern day history rather like the scientific journey towards accurately determining longitude at sea.

“After my academic training on the East Coast, I was lucky enough to be able to go out West for postdoctoral work,” recalled Barnes. “There I spent two years mostly relearning how to do science empirically by hiking Grand Canyon and wandering among the trees of the American Southwest, including those that inspired the founders of dendrochronology.” Dendrochronology is a branch of science concerned with determining the ages of trees by studying tree rings.

“In 2000 (published in 2001) in Madison, Wisconsin, where Soren and I became friends, I was examining the rotation rates of exoplanet host stars and realized that the overwhelming majority were not defined by the presence of planets,” Barnes recalled.

“Rather, their periods, like those of all the other cool stars, changed very simply with only two variables: stellar age and stellar mass. Two additional years of work resulted in my 2003 paper naming and describing gyrochronology.”

Since no one seemed to appreciate that such ages would actually be better than others, he published another paper in 2007, proving that such ages would also be precise.

Jan 4, 2015

Plant geneticists including Sam Hazen at the University of Massachusetts Amherst and Siobhan Brady at the University of California, Davis, have sorted out the gene regulatory networks that control cell wall thickening by the synthesis of the three polymers, cellulose, hemicellulose and lignin.

The authors say that the most rigid of the polymers, lignin, represents "a major impediment" to extracting sugars from plant biomass that can be used to make biofuels. Their genetic advance is expected to "serve as a foundation for understanding the regulation of a complex, integral plant component" and as a map for how future researchers might manipulate the polymer-forming processes to improve the efficiency of biofuel production.

The three key components, found in plant tissues known as xylem, provide plants with mechanical strength and waterproof cells that transport water. Working in the model plant Arabidopsis thaliana, Hazen, Brady and colleagues explored how a large number of interconnected transcription factors regulate xylem and cell wall thickening. Results appeared in an early online edition Dec. 24 in Nature.

An invited commentary in the journal on the significance of this discovery points out that "understanding how the relative proportions of these biopolymers are controlled in plant tissue would open up opportunities to redesign plants for biofuel use."Hazen, Brady and colleagues'study identified hundreds of new regulators and offers "considerable insight," the authors say, "into the developmental regulation of xylem cell differentiation."

Specifically, using a systems approach to identify protein-DNA interactions, they screened more than 460 transcription factors expressed in root xylem to explore their ability to bind the promoters of about 50 genes known to be involved in processes that produce cell-wall components. Hazen says, "This revealed a highly interconnected network of more than 240 genes and more than 600 protein-DNA interactions that we had not known about before."

They also found that each cell-wall gene in the xylem regulatory network is bound by an average of five different transcription factors from 35 distinct families of regulatory proteins. Further, many of the transcription factors form a surprisingly large number of feed-forward loops that co-regulate target genes.

In other words, rather than a series of on-off switches that leads to an ultimate action like making cellulose, most of the proteins including regulators of cell cycle and differentiation bind directly to cellulose genes and to other transcription regulators. This gives plants a huge number of possible combinations for responding and adapting to environmental stress such as salt or drought, the authors point out.

The disco clam, so named because light flashes from its mirrored “lips,” turns out to be the disco ball from hell. New research has found that the clam’s impressive light show attracts prey, which may be rendered immobile by noxious, acidic mucus produced by the busy bivalve.

The unusual findings, reported at the 2015 annual conference of the Society of Integrative and Comparative Biology in West Palm Beach, Fla., solve the mystery as to why the disco clam (Ctenoides ales) puts on such a flashy light show.

At first it was thought that the clam might be trying to woo mates, but that sentiment might have been felt more by researcher Lindsey Dougherty of UC Berkeley. She was thrilled when she first encountered the unique clams in a dark, underwater cave during a dive in Indonesia.

“It was on that trip I first saw the disco clam, and immediately fell in love,” reminisced Dougherty in a press release.

She and her collaborators, Professor Roy Caldwell and undergraduate Alexandria Neibergall, brought some of the clams back to a lab to investigate why and how the clam’s flash.

First, the researchers determined that the flashes are caused by specialized tissues that form a double layer that is reflective to light on one side, but absorbent on the other.

When the tissue along the lip margins of the clam’s mantle is rapidly rolled and unfurled, the reflecting light gives the appearance of flashing. These tissues are so reflective that they can even flash using the low levels of blue light found in the caves. Disco clams are the only species of bivalve to have evolved structural coloration of this kind, according to the researchers.

The team next examined the structure and proteins in the clam’s tiny eyes using a powerful microscope. The researchers concluded the clam’s vision is too poor to allow it to observe displays by other clams. Since the clams aren’t visually attracted to each other, the wooing theory around the light show was tossed out.

The scientists then investigated what would happen if a predator threatened the disco clam.

“In this case, the false predator was just a styrofoam lid,” Dougherty said. “But it turns out a styrofoam lid is indeed pretty scary to the clams, because their flash rate almost doubled from just under 2 Hz to just under 4 Hz.”